Alpha, beta-butenolide preparation

ABSTRACT

A method for preparing an alpha,beta-dehydro-gamma-butyrolactone which comprises contacting a carboxylic acid of the formula ##STR1## wherein R is H or C 1  to C 10  alkyl group, with oxygen and a catalyst comprising a noble metal halide, a variable valence transition metal halide and an alkali metal halide at a temperature between 50° and 300° C and superatmospheric pressure.

BACKGROUND OF THE INVENTION

The present invention is directed to the preparation of alpha,beta-dehydro-gamma-butyrolactone which, in turn, can be converted to gamma-butyrolactone by hydrogenation of the double bond. The alpha,beta-unsaturated lactone is useful as a solvent or monomer but, more particularly, upon hydrogenation the resulting gamma-butyrolactone is valuable to make the corresponding lactam as by reaction with ammonia. The lactam can be used to make fibers such as nylon fibers.

Previously gamma-butyrolactone has been made by converting gamma-hydroxycarboxylic acids to the lactone as follows: ##STR2## See, for example, Cason, Principles of Modern Organic Chemistry, Prentice-Hall, Inc., 1966.

Morrison and Boyd, Organic Chemistry, 2nd Ed., Allyn and Bacon, Inc., Boston, 1970, give the reaction as follows for the salt of a gamma-hydroxy acid: ##STR3##

Commercially gamma-butyrolactone is made from 1,4-butanediol by oxidative cyclization. However, the diol is believed to first be converted to the hydroxy acid before the cyclization occurs so that the cyclization would be as given in the above equations.

Previous methods of making alpha,beta-dehydro-gamma-butyrolactone, which may also be referred to as alpha,beta-butenolide, include a multistep process in which 3-butenoic acid is first converted into the corresponding epoxide by reaction with performic acid; the epoxide is then treated with hydrochloric acid to effect cyclization to a hydroxylactone, and finally this hydroxylactone is dehydrated over polyphosphoric acid to the unsaturated lactone. R. Palm, H. Ohse, and H. Cherdon Angew. Chem. Int. Ed. Engl. 5, (12), 994 (1966).

SUMMARY OF THE INVENTION

According to the present invention a method is provided for preparing an alpha,beta-dehydro-gamma butyrolactone which comprises contacting a carboxylic acid of the formula ##STR4## wherein R is H or C₁ to C₁₀ alkyl group, with oxygen and a catalyst comprising a noble metal halide, a variable valence transition metal halide and an alkali metal halide at a temperature between 50° and 300° C and superatmospheric pressure.

Preferred operating conditions for the method of the present invention are as follows:

    ______________________________________                                                            More      Most                                                        Preferred                                                                               Preferred Preferred                                         ______________________________________                                         Temperature, ° C                                                                    50-175     50-150    75-125                                        Pressure, atm.                                                                             .1-100     5-30      7-20                                          Oxygen partial                                                                 pressure, atm.                                                                             .1-100     1-25      5-20                                          Feed        --         --        3-butenoic acid                               Solvent     organic acids                                                                             3-butenoic                                                                               3-butenoic acid                                           nitriles   acid                                                                3° amides                                                                          benzonitrile                                             Catalyst (e.g. Pd or                                                                       ##STR5##                                                                                  ##STR6##                                               Pt/Cu/Li)   sulfoxides dimethyl-                                                                      acetamide                                               PdCl.sub.2, PtCl.sub.2 mol %                                                               .01-10     0.5-5     1-5                                           CuCl.sub.2 mol %                                                                           .1-40      3-30      5-25                                          LiCl mol %  .1-50      5-40      10-30                                         ______________________________________                                    

The term "noble metal catalyst" is used herein to mean ruthenium, rhodium, palladium, osmium, iridium and platinum. Palladium and platinum are particularly preferred noble metal catalysts for the present preparation method.

The term "variable valence transition metals" is used herein to mean those transition metals which can change their valence by state of oxidation-reduction more specifically metals, which can be oxidized to their higher oxidation state by air or oxygen. Preferred transition metal catalysts are copper and iron. Particularly preferred as the transition metal catalyst is copper, especially as CuCl₂.

The term "alkali metal" is used herein to mean Group IA metals. Of these metals lithium, sodium, and potassium are preferred and lithium is especially preferred.

One unexpected aspect of the present invention is that the cyclization reaction appears to occur in an anti-Markovnikov fashion, although the present invention is not to be limited by the hypothesized method for the reaction. The reaction equation is indicated as follows for the 3-butenoic acid feed: ##STR7##

In the above equation the cyclization reaction appears to occur by a route wherein the carboxyl oxygen is attached to the terminal carbon atom, which has more hydrogen atoms than does the internal double bond carbon atom. In a Markovnikov-type addition the negatively charged carboxyl oxygen would be expected to attach to the internal carbon atom similar to the reaction of hydrogen bromide with propylene wherein 2-bromo-propane is formed according to the normal Markovnikov reaction with the negatively charged bromide group going to the internal double bond carbon atom, which has fewer hydrogen atoms than does the terminal doubly bonded carbon atom.

My concurrently filed and related application Ser. No. 671,880 titled "4-Pentenoic Acid Conversion", illustrates a reaction wherein a lactone is formed with the carboxyl group attaching to the internal carbon atom in what may be regarded as a normal Markovnikov addition position for the cyclization reaction.

EXAMPLES

As indicated in the Tables below, butenoic acid, solvent and catalyst were charged into a glass pressure reactor provided with a magnetic stirrer. The catalyst was a homogeneous catalyst in the liquid phase. The reactor was connected to a gas reservoir through a pressure regulator. Sufficient oxygen was added to bring the pressure to 100 psig, and the reactants were then heated to the reaction temperature. The pressure was adjusted to the desired value and the reaction continued at constant pressure.

Upon completion, the reactor was depressured and the products analyzed by gas chromatography. When two phases were present tetrahydrofuran was added prior to analysis.

Alpha,beta-butenolide was separated out by distillation and identified by spectral comparison with an authentic sample prepared by the procedure of R. Palm et al, Angew, Chem. Int. Ed., Engl., 5 (12), 994 (1966). The data summarized in Tables I through V illustrates that yields of 40 to 50 mol % and higher of alpha,beta-butenolide can be achieved using the process of the present invention. Run No. 18 in Table V also illustrates that, if desired, the reaction can be carried out in the absence of oxygen gas by using lithium acetate and a stoichiometric amount of cupric chloride.

                  TABLE I                                                          ______________________________________                                         Run   PdCl.sub.2                                                                               Time    Conv.  Yield                                           No.   mmol      Hr.     %      mol %  Id. No.                                  ______________________________________                                         1     1.15      1       88.8   34.5   B2066-24                                 2     2.4       1       76.6   40.3   B2066-05                                 3     4.6       1       94.1   44.3   B2066-20                                 4     9.2       1       92.6   47.8   B2066-22                                 5     18.0      1       84.2   34.4   B2102-22                                 Charge:                                                                        3-Butenoic Acid    100      mmol                                               Toluene            32.6     "                                                  LiCl               30.2     "                                                  CuCl.sub.2         19.9     "                                                  PdCl.sub.2         as shown                                                    Temperature = 100° C                                                    Pressure = 100 psig O.sub.2                                                    ______________________________________                                    

                  TABLE II                                                         ______________________________________                                         Run   CuCl.sub.2                                                                               Time     Conv.  Yield                                          No.   mmol      Hr.      %      mol %  Id. No.                                 ______________________________________                                         6     5         1        69.3   17.9   B2066-06                                7     10        1        61.8   34.3   B2009-33                                8     20        1        76.6   40.3   B2066-05                                9     20        1/2      35.4   34.2   B2066-09                                10    38        1        71.3   34.2   B2066-08                                Charge:                                                                        3-Butenoic Acid    100      mmol                                               Toluene            32.6     "                                                  LiCl               30.2     "                                                  CuCl.sub.2         as shown                                                    PdCl.sub.2         2.4      mmol                                               Temperature = 100° C                                                    Pressure = 100 psig O.sub.2                                                    ______________________________________                                    

                  TABLE III                                                        ______________________________________                                                                               Yield                                    Run  PdCl.sub.2                                                                             CuCl.sub.2                                                                             Solvent                                                                              Time Conv. mol                                      No.  mmol    mmol    ml    Hr.  %     %    Id. No.                             ______________________________________                                         11   9.5     60.2    Benzo-                                                                               1    91.4  56.1 B2066-43                                                 nitrile                                                                        50                                                        12   9.4     20.0    Benzo-                                                                               1    81.4  26.0 B2066-44                                                 nitrile                                                                        50                                                        13   18.2    20.0    --    1/2  73.5  30.1 B2066-39                            14   18.2    60.4    --    1/2  76.5  29.3 B2066-41                            Charge:                                                                        3-Butenoic Acid                                                                              90     mmol    Solvent as shown                                  Toluene       32     "       Temperature = 100° C                       LiCl          30     "       Pressure = 100 psig O.sub.2                       PdCl.sub.2 , CuCl.sub.2                                                                      as shown                                                         ______________________________________                                    

                  TABLE IV                                                         ______________________________________                                                           Sol-              Yield                                      Run       CuCl.sub.2                                                                             vent   Time Conv. mol                                        No.       mmol    ml     Hr.  %     %    Id. No.                               ______________________________________                                         15   KPtCl.sub.4                                                                             20      --   2    12.2  93.2 B2066-50                            15a  1 mmol                16   87.2  33.3                                     16   PtCl.sub.2                                                                              20      --   2    38.6  53.9 B2102-08                                 2.4mmol                                                                   17   PdCl.sub.2                                                                              20      --   1    76.6  40.3 B2066-05                                 2.4mmol                                                                   Charge:                      Solvent as shown                                  3-Butenoic Acid                                                                              90     mmol    Temperature = 100° C                       Toluene       32     "       Pressure = 100 psig O.sub.2                       LiCl          30     "                                                         Catalyst as shown                                                              ______________________________________                                    

                                      TABLE V                                      __________________________________________________________________________     Run     Catalyst     Temp                                                                              Time                                                                               Conv.                                                                               Yield                                         No.     (mmol)       ° C                                                                        Hr. %    mol %                                                                               Id. No.                                  __________________________________________________________________________     18 PtCl.sub.2 (2.3)-CuCl.sub.2 (116)-LiOAc(130)                                                     100                                                                               2   61.8 50.7 B2231-16.sup.1                           18a                     4   80.9 48.9 B2231-16.sup.1                           19 PtCl.sub.2 (2.3)-CuCl.sub.2 (116)-LiCl (60)                                                      100                                                                               2   30.8  0   B2231-13.sup.1                           20 PtCl.sub.2 (2.3)-CuCl.sub.2 (30.5)-LiOAc (15)                                                    100                                                                               3   66.4 42.sup.4                                                                            B2163-44                                 21 PtCl (2.3)-CuCl.sub.2 (30.5)-LiOAc(15)                                                           100                                                                               3   79.7 30.8 B2163-45                                 22 PtCl.sub.2 (2.3)-CuCl.sub.2 (30.5)-LiCl (15)                                                     100                                                                               3   100.0                                                                               45.5.sup.2                                                                          B2163-49                                 23 PtCl.sub.2 (2.3)-CuCl.sub.2 (30.5)-LiCl (60)                                                     100                                                                               2   100.0                                                                               45.0 B2231-10                                 24 PtCl.sub.2 (2.3)-CuCl.sub.2 (30.5)-LiCl (15)-                                   LiOAc (15)       100                                                                               2.5 86.2 49.1.sup.2                                                                          B2231-06                                 25 PtCl.sub.2 (2.3)-CuCl.sub.2 (10)-LiCl (15)-                                     LiOAc (15)       100                                                                               2.5 64.7 32.5 B2231-16                                 26 PtCl.sub.2 (2.3)-CuCl.sub.2 (30.5)-LiCl (30)                                                     room                                                                              88  9.0   0   B2231-09                                                      temp                                                      Charge:                                                                        3-Butenoic Acid                                                                          58 mmol          Pressure = 100 psig O.sub.2 (unless                 HOAc      25 ml             otherwise indicated)                               Toluene   32 mmol          .sup.1 Under 100 psig N.sub.2                       Catalyst as shown          .sup.2 Includes small amount of                                                 crotonic acid                                      __________________________________________________________________________

                  TABLE VI                                                         ______________________________________                                         Run    Temp.,   Time,    Conv.,  Yield,                                        No.    ° C                                                                              hrs.     %       %     Id. No.                                 ______________________________________                                         27     60       2        100     34.5  B2102-18                                28     80       1        41.3    36.2  B2102-16                                28a    80       2        100     33.0  --                                      29     100      1        91.4    56.1  B2066-45                                30     120      .5       90      42    B2102-34                                31     60       2        100     34.5  B2102-13                                31a    60       3        100     38.6  --                                      32     40       .67      87.3    39.8  B2102-38                                32a    100      1        100     52.1  --                                      Charge:                                                                        3-butenoic acid    88       mmol                                               benzonitrile       50       ml                                                 toluene            32       mmol                                               LiCl               30       mmol                                               CuCl.sub.2         60       mmol                                               PdCl.sub.2         9.4      mmol                                               ______________________________________                                    

                  TABLE VII                                                        ______________________________________                                         Run             Time,    Conv., Yield,                                         No.   Catalyst  hrs.     %      %      Id. No.                                 ______________________________________                                         33    PdCl.sub.2                                                                               2        20     58.4   B2102-27                                Charge:                                                                        PdCl.sub.2          20      mmol                                               3-butenoic acid     80.5    mmol                                               benzonitrile        50      ml                                                 toluene             32.2    mmol                                               oxygen             none                                                        nitrogen           100      psig                                               Temperature        100° C                                               ______________________________________                                    

Run No. 33 was carried out using a stoichiometric amount of PdCl₂, that is, 20.5 mmol, and using no oxygen. In this method of operation, the 3-butenoic acid was oxidized to the product lactone, and the PdCl₂ was reduced to Pd and HCl. In the presence of HCl, the Pd could be oxidized back to PdCl₂ in a separate reaction zone in the presence of copper chloride using air or oxygen.

However, as shown by the conversion and yield in Table VII, I found that in this method of operation relatively low amounts of the product lactone were obtained, compared to operation in accord with the present invention. 

What is claimed is:
 1. A method for preparing an alpha,beta-dehydro-gamma-butyrolactone which comprises contacting a carboxylic acid of the formula ##STR8## wherein R is H or C₁ to C₁₀ alkyl group, with oxygen and a catalyst comprising a noble metal halide, a copper or iron halide and an alkali metal halide at a temperature between 50° and 300° C and superatmospheric pressure.
 2. A process in accordance with claim 1 wherein the temperature is 75° to 150° C.
 3. A process in accordance with claim 2 wherein the halide is chloride and wherein the noble metal is platinum or palladium, the transition metal is copper, and the alkali metal is lithium.
 4. A process in accordance with claim 3 wherein the reaction is carried out in the presence of an inert hydrocarbon solvent.
 5. A process in accordance with claim 4 wherein the solvent is 3-butenoic acid.
 6. A process in accordance with claim 3 wherein the carboxylic acid feed is 3-butenoic acid.
 7. A process in accordance with claim 3 wherein the catalyst comprises 0.1 to 10 parts platinum or palladium chloride, 1 to 40 parts cupric chloride, and 1 to 50 parts lithium chloride wherein the parts are on a molar basis.
 8. A process in accordance with claim 1 wherein the halide is chloride. 